Ankle Measurements of Arterial Pressure: Semi-recumbent or Horizontal Position.

The upper arm is sometimes inaccessible for arterial pressure (AP) measurement. Placing the automatic cuff at the ankle is a common alternative. However, whether AP measurement at the ankle is reliable is uncertain. Furthermore, it is unknown whether it is necessary to place the patient in a horizontal position to improve the reliability of the measurement, or if leaving the patient in default position (often semi-recumbent) is acceptable. The aim of this study is to answer these questions. Additionally, investigators will evaluate whether a smartphone application that allows for the simple measurement of AP (by gently placing a finger on the camera lens) is a valuable alternative to upper arm measurements.